Apparatus for the manufacture of earth metals



.April 13' ,'1926.

- H. DOLTER APPARATUS FOR THE MANUEACTURE oF EARTH METALS Filed Oct. 27

v A IIHHMNIH I April 13 1926. 1,580,469 H. DOLTER APPARATUS Fon THEMANUFACTURE oF EARTH'METALS Filed ot..27, 1 924 's sheets-sneu 2 April13, 192s. `1,580,469

- H. DOLTER APPARATUS FOR THE MANUFACTRE- OF EARTH METALS Filed oct. 27,1924 s sheets-shed s plates covering the tank ratus resides in thatPatented Apr. 13, 1926 Pari-:Nry orrica.

HENRI DOLTER, OF LIMOGES, FRANCE.

APPARATUS FOB THE MANUFACTURE 0F EARTH METALS.

Application tiled October 27, 1924. Serial No. 746,149.

Metals, of which the following is a specifi-- cation.

The present invention has for its object an apparatus for themanufacture of earth metals and articularly ada )ted for carrying outtheimproved metho of electrolytic manufacture ot said metals which consistsin melting the electrolyte within the electroic tank and maintaining thesaidelectrote in the liquid state, by means of gas raiators andpreferably nameless combustion gas radiators, immersed within theelectroyte.

One advantage of the use of my new appathe electric current is now yusedsolely to decompose the already melted electrolyte, whereby I obtain agreat econom in electric power, which considerably re uces the cost ofthe metal.

A further feature of my improved appara` tus consists in that theelectrolytic tank forming part of the apparatus, has a low electricresistance, whic i is possible since no Joule e'ect for heating theelectrolyte and melt-ing the same is now necessary, and which permits ofconnecting in series a greater number of tanks than is admissible withthe known apparatus, and hence of employin electric generators of usualconstruction an working normally at usual voltage.

The appended drawings show by way of exam le an embodiment of theapparatus accor ino to the invention and particularly ada ted or themanufacture of aluminium.

ig. 1 is a plan view of the apparatus, the

being removed.

Fig. 2 is a cross section on the line 242, Fic. 1.

Fig. 3 is a longitudinal section of the tank on the line 33, Fig. i.

Fig. 4 is a diagrammatic plan view ot a plant consisting of'a pluralityaccording to the said invention.

The apparatus,'or eleotrolytic tank, com prises a metallic tank i. whichis strengthcned by outer iron fittings 2 and is line with a goodelectric conducting substance 3 which preferably consists of bricks ofconiprcssed coal or pretroleum coke and the faces ot apparatus whereofare plunished alter baking. Said bricks are jointed by means of a liquidmortai' oi thc suine material made up with glucose and ground into animpalpablc powder. In certain cases it may prove advantageous to coverthe parts ot` the said lining which are not to enter into Contact withthe electrol te withv a metallic coating, for instance of t ie samemetal than that produced in the tank, of an electrolytic deposit orobtained by spraying pulverized metal by means of any known apparatussuch as a Schopp pistol. But in the particular case of the productionvof aluminium, this layer is not required.

The resulting tank will form an excellent conducting mass and it isconnected to negative pole of the source of current. The tank and itslining are electrically insulated from earth by insulating supports lmade ot i any suitable substance.

The apparatus comprises also gas radiators designed for heating theelectrolyteand melting the same within the tank; said radiators com riseone, two or a greater number of meta lic tubes 5, for exam le of steelor nickel, extending longitudinally through the tank and Ldisposed inrecesses 6 formed in the' conducting lining of the tank. Said tubes areelectrically connected to the tank 1, i. e., to the cathode, in order toobviate any difference of potential between the radiators and the innerlining of the tank, whereby all chemical action upon the tubes will beavoided. For this purpose, the said tubes are immersed in a mass ofmelted aluminium 7 filling each of the recesses 6, said mass being forexam le obtained during the first operation per ormed in the tank andconsisting ottheportion of melted metal which is situated below theinlet 8 of the channel 9 for pourin the metal, said channel beingnermally c osed by a carbon plug 35.

The above described means for conuectin the radiator tubes to theelectrolytic tan;

is found to be particularly advantageous in the manufacture ofaluminium. Butl it is obvious that the tubes may be connected to thecathode in any'other suitable manner; for exam le the various radiatortubes may be secure or suspended to a removable med tallic cross-piececarried by the tank, the

saine being directly electrically connected to the negative pole of thesource of current or to the walls ofthe tank. ln this event, in

or of copper, said layer being formed thei " providing for the heatingof order to avoid all oxidation and consequent destruction of the saidtubes,y these latter must be covered with a layer of the same metalwhich is produced in the tank, aluminium in the present case, saidlayerbeing formed of an electrolytic deposit or obtained by sprayingpulverized metal by any known suitable means.

The tubes 5 are filled with a granular and porous refractory substanceas is usually employed in iameless combustion gas radiators.

The inlet end of each tube 5 is connected to a combustible gas supplypipe and to a compressed air pipe, but is electrically insulatedtherefrom, said connection being effected in the following manner.

The inlet of each tube 5 is connected by a flange 10 to a socket/11 intowhich open a branch pipe 12, of the gas supply main pipe and a branchpipe 13 of the air main pipe. Said branch pipe 12 is connected to thesocket 11 by an electrically insulating section of pipe 111 (e. g., ofporcelain). The compressed air branch pipe 13 is connected to the socketl1 by an insulating section 15 and a pipe 16 which is surrounded for apart of its length by a casing 17 which communicates, through the mediumof a three-way priming cock 18, with the burnt gas outlet end of asecond tube 5 adjacent the inlet end under consideration and situated atthe same side of the apparatus. The casing or jacket 17 'thusconstitutes a heat exchanger the compressed air before the latter ismixed with the combustible gas in each of the sockets 11. The casing 17is also connected to the main exhaust pipe of the plant by an insulatingsection 19 and a branch element 36. In this manner, the set of radiatortubes 5, connected to the cathode, is well insulated from the outerpiping of the plant. It will be seen in the drawing that, due to thisarrangement, the apparatus comprises at each end like connectionsof thetubes 5 with the gas and the compressed air supply pipes and with theexhaust pipes and that the gases are circulated in opposite directionsin any two adjacent tubes, according to the arrows 28 and 29.

Although the radiators shown in the drawing consist of straight metallictubes, it -is obvious that the tubes may be given any other suitableshape, and may be made of any other suitable substance having a goodheat-conduction, for example graphite,

alumina or silica.

The anode which is immersed in the tank comprises one or more carbonblocks 20, each having imbedded therein a metal sus` pension rod 21. Theupper part of each rod forms a rack 22, or is provided with a screw,said rack or screw being operated in any known manner, either by hand orVby .lum `may be constituted series for instance forty apparatus suc as1,5so,aca

means of a small electric motor, so that it may be raised orlowered-automatically or not-according to the electric resistance of thesaid tank. The said electrode is connected to the positive pole of thesource of current.

The tank may be covered by suitable plates 23 which are for example ofcarbon, caving however a suiicient passage way for the anode. Thesaidplates are provided with apertures 24 which are closed during theinitial melting period by plugs provided with handles, and through whichsuitable quantities of salts and oxides are supplied from time to time;said apertures also provide for theescape of the gases-produced in thetank.

Each operation carried out in the above lescribed apparatus is performedas folows: v

The salts or oxides constituting the electrolyte, i. e., a mixture ofalumina and cryolite are first introduced into the tank; the gas supplyvalves 25 of the radiators are opened, and the three-way cocks 18 areturned so as to connect the interior of the tubes 5 directl to theatmosphere through the medium ofythe nozzles. 26 of the cocks 18. Thegas issuing from said nozzles 264 is thus ignited and the air supplycocks 27 alumina are supplied according as the alu# mina becomesdissolved, and when the bath has attained the normal composition, theelectric current is sent into the tank; further quantities of aluminaare supplied according as the aluminium is deposited.

As above indicated, the position of the anode, according to theresistance of the whole apparatus (i. e., tank and bath), can beregulated automatically in the known manner by means of an electricmotor controlled by a relay.

At stated intervals, the metal in the tank,

is cast by removing the carbon plug 35 normally closing the channel 9. I

Inasmuch as the tank and its lining are so constructed as to have but alow electricl resistance, and on the other hand the E. M. F.

required for the decomposition of the.

alumina varies from 28 to 3 volts, a complete plant for the manufactureof aluminby connecting in herein described, thus allowing the use ofknown types of electric generators working normally at thc usual volts.

A plant of this nature is shown diagrammatically in Fig. 4. and saidfigure shows that i'or each of the successive apparatus 30, the anode isconnected to the tank of the succeeding apparatus, the anode ot thefirst apparatus bein(r alone connected to the ositive terminal ot thesource of current, whilst the tank ot the last apparatus is connected tothe corresponding negative terminal. For each apparatus, the respectivepipes l2, 13 and 36 for the gas and the compressed air supply and theexhaustof the combustion gases, are connected to the respective lnaiiipipes of the plant 32, 83 and 34 forl the gas and the compressed air suply and for the discharge. y,

viously, the said invention is not limited to the use ot theabove-mentioned details of construction of the apparatus, `these beingsusceptible of all desired modifications Without departing from thespirit ot the invention.

Having now described my invention, I declare that what I claim as ner.and desire to secure by Letters Patent is:

1. In an electrolytic tank for the manufacture of earth metals, thecombination of tubes extending throu h the tank, means for supplying acombusti le gas to said tubes, means for supplying compressed air tosaid tubes anda Vrraniilar and porous refractory r substance within saidtubes, whereby a lameless combustion is obtained.

2. In an electrolytic tank for the manufacture of earth metals, the.combination of tubes extending through the tank, means for electricallyconnecting. said tubes to the cathode of said tank, means for supplyinga combustible vgas to said tubes, means for supplying com ressed air tosaid tubes, and a granular am porous refractory substance within saidtubes, whereby a nameless com'- bustion is obtained.

3. In' an electrolytic tank for the manufacture of earth metals, thecombination of tubes extending through the tank, means for electricallyconnecting said tubes to the cathode of said tank, a layer of the sainemetal as that produced in the tank covering said tubes, ,means forsupplying a coinbustible gas to'said tubes, means for supplyingcompressed air to said tubes and a granular and porous refractorysubstance Within said tubes, whereby a nameless combustion is obtained.

s". In an electrolytic tank for the manufacture of earth metals, thecombination et tubes extending through the tank` means for electricallyconnecting said tubes to the cathode of said tank, a layer ot the sameinetal as that produced in the tank covering said tubes, pipes forsupplying a conivoltage of 110 to 12() bustible gas to said tubes, pipesfor supplying compressed air to said tubes, exhaust pi es fordischarging the burnt gases from said tubes, electrically insulatingmembers for connecting said pipes to said tubes and a granular andporous refractory substance Within said tubes, whereby a Ilamclesscouibust-ion is obtained. l

5; In an electrolytie tank for the manufacture of earth metals, thecombination et tubes extending through the tank, means for electricallyconnecting said tubes to the cathode of said tank, a layer ot the samemetal as that produced in the tank covering said tubes, pipes forsupplying a combustible gas Ito said tubes, pipes for supplyingcompressed air -to said tubes, exaust pipes 'for discharging the burntgases from said tubes, the exhaust pipe o one tube surrounding a portionof the air supply ipe for an adjacent tube, electricallyinsu atingmembers for connecting said pipes `to said tubes and a granular andporous refractory substance Within said tubes, whereby a flameless'combustion is obtained. 6. An electrolytic tank for the manufacture ofearth metals comprisin in combination a metal tank, an 'inner dining ofcarbon bricks for said together with said lining constituting thecathode of the a paraus, tubes extending through the tank elow thenormal level of the electrolyte in said tank, means for electricallyconnecting said tubes to said tank,` means for supplying a combustiblegas to said tubes, means for supplying compressed air to said tubes anda granular and porous refractory substance within said tubes, whereby afiameless combustion is obtained.

7. An electrolytic tank forthe manufacture of earth metals comprising incombination: a metal tank, an inner lining of carbon bricks for saidtank, said bricks having all their faces planished, the tank togetherWith said lining constituting the cathode of the apparatus, a layer ofthe same metal as that produced in the tank coating the portions of. thetank walls above the normal level of the electrolyte ir. said tank,tubes extending through the tank below the normal level ot means forelectrically connecting said tubes to said tank, means for supplying acombustible gas to said tubes, means for sup- `plyin compressed air tosaidtubes and a granu ar and porous refractory substance Within saidtubes, whereby a flameless conibustion is obtained.

8. An electrolytic tank ture of anl aluminium comprising in com-'.bination: a metal tank, an inner lining ot carbon bricks for saidtanks, said bricks having all their faces planished, the tank tank, saidbricks I having all their faces planished, the tank` for the manufacllOthe electrolyte in said tank,

togetherwith said lining constituting the cathode of the apparatus,channels formed in the bottom Wall 'of said inner lining, cast aluminiumfilling said channels, tubes eX- 5 tending through said channels andimbedded Within said cast aluminium, means for supplying a combustiblegas to said tubes, means for supplying compressed air to said tubes anda granularfand porous refractory substance within said tubes, whereby ailameless combustion is obtained. In testimony whereof I have signed myname to this specification.

V HENRI DOLTER.

